path: root/Documentation
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authorAndi Kleen <ak@suse.de>2008-01-30 13:33:21 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-30 13:33:21 +0100
commitac72e7888a612dccfbc15b34698aad441bdfda10 (patch)
treeabd99cb2ad8ddfd7f695bcfbe6eb9b6e1183ed3d /Documentation
parent191679fdfa63342752ff6a094a2522ae939b8d0c (diff)
x86: add generic clearcpuid=... option
Add a generic option to clear any cpuid bit. I added it because it was very easy to add with the new generic cpuid disable bitmap and perhaps it will be useful in the future. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation')
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 040e30a33b7..50d564dabb1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -416,6 +416,19 @@ and is between 256 and 4096 characters. It is defined in the file
[SPARC64] tick
[X86-64] hpet,tsc
+ clearcpuid=BITNUM [X86]
+ Disable CPUID feature X for the kernel. See
+ include/asm-x86/cpufeature.h for the valid bit numbers.
+ Note the Linux specific bits are not necessarily
+ stable over kernel options, but the vendor specific
+ ones should be.
+ Also note that user programs calling CPUID directly
+ or using the feature without checking anything
+ will still see it. This just prevents it from
+ being used by the kernel or shown in /proc/cpuinfo.
+ Also note the kernel might malfunction if you disable
+ some critical bits.
code_bytes [IA32/X86_64] How many bytes of object code to print
in an oops report.
Range: 0 - 8192